Disc playback apparatus

ABSTRACT

A disc playback apparatus characterized in, when receiving either a fast-forward playback request or a fast-backward playback request, calculating a target address by setting up a position which is close to a position at which information being read from a memory and being played back is stored in a disc as a movement destination of an optical pickup, and moving the optical pickup to the above-mentioned target address.

FIELD OF THE INVENTION

The present invention relates to a disc playback apparatus having afunction of preventing skipping.

BACKGROUND OF THE INVENTION

A conventional disc playback apparatus temporarily stores informationwhich is read from a disc by an optical pickup in an external memory,and then reads the information stored in the external memory to playback the information, in order to prevent skipping at the time of thedisc playback which results from simplification of a vibration-proofsystem which is caused by the downsizing of the disc playback apparatusand incorporation of a plurality of discs into the disc playbackapparatus. Therefore, a position (referred to as a pickup position fromhere on) at which the optical pickup reads the information stored in thedisc differs from a position (referred to as a playback position fromhere on) at which the information which is being read from the externalmemory and is being played back by the disc playback apparatus is storedin the above-mentioned disc, and, when receiving a request for either afast-forward playback or a fast-backward playback at the time of aplayback of the disc, the disc playback apparatus has to start either afast-forward playback process or a fast-backward playback process afterfirst returning the position of the optical pickup to the playbackposition.

The operation of the disc playback apparatus will be explainedhereafter.

FIG. 4 is a flow chart showing the operation of the conventional discplayback apparatus having the skipping preventing function at the timeof performing a fast-forward (or fast-backward) playback process. When auser makes a request for either a fast-forward playback or afast-backward playback, the conventional disc playback apparatus sets upthe playback position as the movement destination of the optical pickup(step ST301). The disc playback apparatus then performs a mute settingon the audio being played back (step ST303), and erases (clears) theinformation stored in the external memory (step ST304). The discplayback apparatus then moves the optical pickup to (makes the opticalpickup search for) the playback position which has been set as themovement destination (step ST305), and reads information stored in thedisc and writes and stores the information in the external memory aftercompleting the movement of the optical pickup (step ST306).

Next, the disc playback apparatus reads the information stored in theabove-mentioned external memory (step ST307), and releases the audiomute setting and outputs an audio and also outputs time information(step ST308). When then receiving a request for a fast-forward playback,the disc playback apparatus sets up a position which is locatedforwardly, by a fixed time, from the playback position as the movementdestination of the optical pickup, whereas when then receiving a requestfor a fast-backward playback, the disc playback apparatus sets up aposition which is located backwardly, by a fixed time, from the playbackposition as the movement destination of the optical pickup (step ST309).In this case, steps ST302 and ST310 are the loop ends of either thefast-forward playback process or the fast-backward playback process, thedisc playback apparatus repeats the processes of steps ST302 to ST310unless either the fast-forward playback or the fast-backward playback isreleased.

FIG. 5 is a flow chart showing the operation of the conventional discplayback apparatus having the skipping preventing function at the timeof releasing the fast-forward playback (or fast-backward playback). Whenreceiving a request for release of either the fast-forward playback orthe fast-backward playback while performing either the fast-forwardplayback or fast-backward playback process, the conventional discplayback apparatus makes an audio mute setting (step ST401), and erases(clears) the information stored in the external memory (step ST402). Thedisc playback apparatus then moves the optical pickup to the positionwhich the disc playback apparatus has set as the movement destination(step ST403), and reads information stored in the disc and writes andstores the information in the external memory after completing themovement of the optical pickup (step ST404). Next, the disc playbackapparatus reads the information stored in the above-mentioned externalmemory (step ST405), and releases the audio mute setting and outputs anaudio while outputting time information (step ST406). The disc playbackapparatus then returns a normal audio playback process.

Furthermore, when failing in reading information from the disc, theconventional disc playback apparatus makes an audio mute setting, andmoves the optical pickup to a position at which the disc playbackapparatus can read information from the disc (makes the optical pickupsearch for the position) so as to read information from the position atwhich the disc playback apparatus can play back the disc again. Aproblem is however that while making the above-mentioned search, thedisc playback apparatus neither outputs any audio nor updates thedisplay of the playback time, and therefore the user cannot grasp theplayback status. To solve this problem, there has been provided a discplayback apparatus that, when failing in reading information from adisc, pseudoly updates a display of the playback time duration at timeintervals different from those at which the disc playback apparatusdisplays the playback time duration at the time of a normal playback ofthe disc (for example, refer to patent reference 1).

-   [Patent reference 1] JP, 2006-331550,A

A problem with a conventional disc playback apparatus which isconstructed as mentioned above is that because the movement destinationof the optical pickup does not change from the playback position wheneither a fast-forward playback or a fast-backward playback has beenstarted and either the fast-forward playback or the fast-backwardplayback is released during a time interval between step ST301 and stepST307 of FIG. 4, the position of the optical pickup does not changeforever when a request for either a fast-forward playback or afast-backward playback and release of either the fast-forward playbackor the fast-backward playback are repeated continuously. Another problemis that because the audio is held muted and the time information is notoutputted, any audio is not outputted at all from the speaker and thedisplay time of the display does not vary. A further problem is thatbecause the display time of the display does not vary until the processof step ST308 is completed when a fast-forward playback request has beenmade, the user has an impression that the responsibility of the discplayback apparatus is bad. Because in patent reference 1 only the casein which the disc playback apparatus fails in reading information froman information storage medium is described, the same problem arises inthe disc playback apparatus when a request for a fast-forward playbackprocess and a request for release of the fast-forward playback processare made alternately.

The present invention is made in order to solve the above-mentionedproblems, and it is therefore an object of the present invention toprovide a disc playback apparatus that prevents the position of anoptical pickup from not changing when a request for either afast-forward playback or a fast-backward playback and a request forrelease of either the fast-forward playback or the fast-backwardplayback are repeated continuously.

DISCLOSURE OF THE INVENTION

A disc playback apparatus in accordance with the present invention ischaracterized in, when receiving either a fast-forward playback requestor a fast-backward playback request, calculating a target address bysetting up a position which is close to a position at which informationbeing read from a memory and being played back is stored in a disc as amovement destination of an optical pickup, and moving the optical pickupto the above-mentioned target address.

In accordance with the present invention, when receiving either thefast-forward playback request or the fast-backward playback request, thedisc playback apparatus calculates a target address by setting up aposition which is close to the position at which information being readfrom the memory and being played back is stored in the disc as themovement destination of the optical pickup, and moves the optical pickupto the above-mentioned target address. Therefore, the present inventionprovides an advantage of being able to prevent the position of theoptical pickup from not changing when a request for either afast-forward playback or a fast-backward playback and a request forrelease of either the fast-forward playback or the fast-backwardplayback are repeated continuously.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram showing a featured structure of a disc playbackapparatus in accordance with this Embodiment 1;

FIG. 2 is a flow chart showing the operation of the disc playbackapparatus in accordance with Embodiment 1 at the time of carrying out afast-forward (or fast-backward) playback process;

FIG. 3 is a flow chart showing the operation of a disc playbackapparatus in accordance with Embodiment 2 at the time of releasing afast-forward (or fast-backward) playback process;

FIG. 4 is a flow chart showing the operation of a conventional discplayback apparatus having a skipping preventing function at the time ofcarrying out a fast-forward (fast-backward) playback process; and

FIG. 5 is a flow chart showing the operation of the conventional discplayback apparatus having the skipping preventing function at the timeof releasing a fast-forward (or fast-backward) playback.

PREFERRED EMBODIMENTS OF THE INVENTION

Hereafter, in order to explain this invention in greater detail, thepreferred embodiments of the present invention will be described withreference to the accompanying drawings.

Embodiment 1

FIG. 1 is a diagram showing a featured structure of a disc playbackapparatus in accordance with this Embodiment 1, and the disc playbackapparatus in accordance with this Embodiment 1 is provided with anoptical pickup 2, a signal processing IC (Integrated Circuit) 3, a CPU(Central Processing Unit) 9, and an external memory 8. In addition, thesignal processing IC 3 is provided with a signal decoding means 4, asubcode analyzing means 5, a servo 6, and a memory controller 7 therein,and the CPU 9 is provided with a time information processing means 10, asearch target calculating means 11, a memory 12, and a search controlmeans 13 therein. In this Embodiment 1, an example of calculating amovement destination of the optical pickup by using a time will beexplained.

The optical pickup 2 reads TOC (Table of Contents) information, audioinformation, etc. which are stored in a disc 1. The signal decodingmeans 4 decodes information read by the optical pickup 2. The subcodeanalyzing means 5 performs an analysis process of analyzing a subcode ofinformation about a time among the information decoded by the signaldecoding means 4 so as to acquire time information. Position informationshowing an absolute elapsed time from the start point of each track anda music number is included in this time information, and a searchoperation on the optical pickup 2, etc. are performed on the basis ofthis time information. The servo 6 controls a drive system (not shown)for driving the optical pickup 2 and the disc 1.

The memory controller 7 writes and stores both the audio informationdecoded by the signal decoding means 4 and the time information acquiredby the subcode analyzing means 5 in the external memory 8 while bringingthem into correspondence with each other. Furthermore, the memorycontroller 7 reads both the audio information and the time informationwhich are stored in the external memory 8, and outputs theabove-mentioned audio information to an audio output circuit (not shown)and also outputs the time information to a display means (not shown) byway of the subcode analyzing means 5 and the time information processingmeans 10, and further erases (clears) both the audio information and thetime information which have been read thereby from the external memory8. After D/A (Digital/Analog) converting the above-mentioned audioinformation into a signal, the audio output circuit amplifies the signalby using an amplifier and emits the signal to the air, as an audio, froma speaker. Furthermore, the display means displays a playback timeduration on a display thereof on the basis of the above-mentioned timeinformation.

The time information processing means 10 processes the time informationacquired by the subcode analyzing means 5. The search target calculatingmeans 11 calculates a target address indicating the movement destinationof the optical pickup 2 on the basis of the time information processedby the time information processing means 10. In this case, when the discplayback apparatus is placed in fast-forward playback mode, a positionwhich is close to the playback position and is located forwardly fromthe playback position by an arbitrary time is calculated as the positionof the movement destination of the optical pickup 2. In contrast, whenthe disc playback apparatus is placed in fast-backward playback mode, aposition which is close to the playback position and is locatedbackwardly from the playback position by an arbitrary time is calculatedas the position of the movement destination of the optical pickup 2. Thememory 12 temporarily stores the time information processed by the timeinformation processing means 10. When receiving either a fast-forwardplayback request signal or a fast-backward playback request signal froman operation unit (not shown), the search control means 13 instructs thesearch target calculating means 11 to calculate the target address, andalso instructs a disc control means 14 to move the optical pickup 2 tothe calculated target address (search). The disc control means 14performs a search operation by controlling the servo 6 according to theinstruction from the search control means 13.

Next, the operation of the disc playback apparatus will be explained.

FIG. 2 is a flow chart showing the operation of the disc playbackapparatus in accordance with Embodiment 1 at the time of carrying out afast-forward (or fast-backward) playback process. When receiving eithera fast-forward playback request signal or a fast-backward playbackrequest signal, the search control means 13 instructs the search targetcalculating means 11 to calculate the movement destination of theoptical pickup 2. When receiving an instruction indicating afast-forward playback request from the search control means 13, thesearch target calculating means 11 calculates a position (referred to asa target position from here on) which is located forwardly, by anarbitrary time, from the playback position, as the movement destinationof the optical pickup 2, on the basis of the time information processedby the time information processing means 10. In contrast, when receivingan instruction indicating a fast-backward playback request from thesearch control means 13, the search target calculating means 11calculates a position (referred to as a target position from here on)which is located backwardly, by an arbitrary time, from the playbackposition, as the movement destination of the optical pickup 2, on thebasis of the time information processed by the time informationprocessing means 10.

The search control means 13 then sets the target position calculated bythe search target calculating means 11 as the movement destination ofthe optical pickup 2 (step ST101), and then instructs the disc controlmeans 14 to move the optical pickup 2 to the above-mentioned targetposition. When receiving the instruction from the search control means13, the disc control means 14 instructs the memory controller 7 to stopthe output of the audio information read from the external memory 8 tothe audio output circuit and to erase the information stored in theexternal memory 8. According to the instruction from the disc controlmeans 14, the memory controller 7 stops the output of the audioinformation to the audio output circuit to perform an audio mute setting(step ST103) and also erases the information stored in the externalmemory 8 (step ST104). Furthermore, the disc control means 14 controlsthe servo 6 so as to move the optical pickup 2 to the above-mentionedtarget position (search) (step ST105). When completing the movement tothe above-mentioned target position, the optical pickup 2 starts readinginformation from the disc 1.

The signal decoding means 4 decodes the information which the opticalpickup 2 has read, and outputs the audio information, among the decodedinformation, to the memory controller 7. The memory controller 7 writesand stores both the audio information outputted by the signal decodingmeans 4 and the time information acquired by the subcode analyzing means5 in the external memory 8 while bringing them into correspondence witheach other (step ST106). Furthermore, the memory controller 7 reads theinformation stored in the external memory 8 (step ST107), and releasesthe audio mute setting, outputs the audio information, among the readinformation, to the audio output circuit and also outputs the timeinformation which is brought into correspondence with theabove-mentioned audio information to the display means (step ST108).

Next, when the disc playback apparatus is performing a fast-forwardplayback, the search target calculating means 11 calculates a positionwhich is located forwardly, by an arbitrary time, from the position atwhich the audio played back in step ST108 is stored as a new movementdestination of the optical pickup 2, whereas when the disc playbackapparatus is performing a fast-forward playback, the search targetcalculating means 11 calculates a position which is located backwardly,by an arbitrary time, from the position at which the audio played backin step ST108 is stored as a new movement destination of the opticalpickup 2. The search control means 13 then sets the position calculatedby the search target calculating means 11 as the movement destination ofthe optical pickup 2 (step ST109), and instructs the disc control means14 to move the optical pickup 2 to the above-mentioned new movementdestination. According to the instruction from the search control means13, the disc control means 14 instructs the memory controller 7 to stopthe output of the audio information read from the external memory 8 tothe audio output circuit and to erase the information stored in theexternal memory 8.

Steps ST102 and ST110 are the loop ends of either the fast-forwardplayback process or the fast-backward playback process, the discplayback apparatus in accordance with this Embodiment 1 repeats theprocesses of steps ST102 to ST110 unless the search control means 13receives either a fast-forward playback release signal or afast-backward playback release signal. Because the operation of the discplayback apparatus at the time of releasing either the fast-forwardplayback or the fast-backward playback is the same as that of aconventional disc playback apparatus, the explanation of the operationwill be omitted hereafter.

As mentioned above, when receiving either the fast-forward playbackrequest signal or the fast-backward playback request signal, the discplayback apparatus in accordance with this Embodiment 1 sets up aposition different from the playback position as the movementdestination of the optical pickup 2. More specifically, when receivingthe fast-forward playback request signal, the disc playback apparatussets up a position which is located forwardly, by an arbitrary time,from the playback position as the movement destination of the opticalpickup 2 and then moves the optical pickup 2 to the set-up position asmentioned, whereas when receiving the fast-backward playback requestsignal, the disc playback apparatus sets up a position which is locatedbackwardly, by an arbitrary time, from the playback position as themovement destination of the optical pickup 2 and then moves the opticalpickup 2 to the set-up position as mentioned. Therefore, the presentembodiment offers an advantage of causing the optical pickup 2 to changein its position even when a state in which a fast-forward playback or afast-backward playback has been started and the fast-forward playback orthe fast-backward playback is released during a time interval betweenstep ST101 and step ST107 is repeated continuously. Furthermore, becausethe display time also varies with the change in the position of theoptical pickup 2, the user does not have an impression that theresponsibility of the disc playback apparatus is bad. In this Embodiment1, the disc playback apparatus outputs the time information to thedisplay means in step ST108 of FIG. 2. As an alternative, the discplayback apparatus can output the time information to the display meansafter making an audio mute setting of step ST303. Because the discplayback apparatus promptly updates the playback time duration displayedon the display by doing in this way, there is provided an advantage ofimproving the responsibility of the disc playback apparatus to the user.

Embodiment 2

In Embodiment 1, the example in which when receiving the fast-forwardplayback request signal or the fast-backward playback request signal,the disc playback apparatus sets up a position which is close to theplayback position as the movement destination of the optical pickup 2will be explained. In contrast, in this Embodiment 2, an example inwhich when receiving a fast-forward playback release signal or afast-backward playback release signal, a position which is locatedforwardly from a position (referred to as a release position from hereon) at which information read from a memory and played back at the timeof the reception of the above-mentioned request is stored in the disc asthe movement destination of the above-mentioned optical pickup 2 will beexplained. Because a disc playback apparatus in accordance with thisEmbodiment 2 has the same structure as the disc playback apparatus inaccordance with Embodiment 1, the explanation of the structure will beomitted hereafter. Also in this Embodiment 2, an example in which thedisc playback apparatus calculates the movement destination of theoptical pickup by using a time will be explained.

Next, the operation of the disc playback apparatus will be explained.

FIG. 3 is a flow chart showing the operation of the disc playbackapparatus in accordance with Embodiment 2 when releasing a fast-forward(or fast-backward) playback. When receiving either a fast-forwardplayback release request signal or a fast-backward playback releaserequest signal, a search control means 13 instructs a search targetcalculating means 11 to calculate the movement destination of theoptical pickup 2. When receiving an instruction indicating thefast-forward playback release request from the search control means 13,the search target calculating means 11 then calculates a position(referred to as a release-time target position from here on) which isclose to the release position and is located forwardly, by an arbitrarytime, from the release position, as the movement destination of theoptical pickup 2. In contrast, when receiving an instruction indicatingthe fast-backward playback release request from the search control means13, the search target calculating means 11 then calculates a position(referred to as a release-time target position from here on) which isclose to the release position and is located backwardly, by an arbitrarytime, from the release position, as the movement destination of theoptical pickup 2.

The search control means 13 then sets up the release-time targetposition calculated by the search target calculating means 11 as themovement destination of the optical pickup 2 (step ST201), and instructsa disc control means 14 to move the optical pickup 2 to theabove-mentioned release-time target position. When receiving theinstruction from the search control means 13, the disc control means 14instructs the memory controller 7 to stop the output of the audioinformation read from an external memory 8 to an audio output circuit,and to erase the information stored in the external memory 8. Accordingto the instruction from the disc control means 14, the memory controller7 stops the output of the audio information to the audio output circuitto perform an audio mute setting (step ST202) and also erases theinformation stored in the external memory 8 (step ST203). Furthermore,the disc control means 14 controls a servo 6 so as to move the opticalpickup 2 to the above-mentioned release-time target position (search)(step ST204). When completing the movement to the above-mentionedrelease-time target position, the optical pickup 2 starts readinginformation stored in the disc 1.

A signal decoding means 4 then decodes the information which the opticalpickup 2 has read, and outputs the audio information, among the decodedinformation, to the memory controller 7. The memory controller 7 writesand stores both the audio information outputted by the signal decodingmeans 4 and the time information acquired by a subcode analyzing meansin the external memory 8 while bringing them into correspondence witheach other (step ST205). Furthermore, the memory controller 7 reads theinformation stored in the external memory 8 (step ST206), and releasesthe audio mute setting, outputs the audio information, among the readinformation, to the audio output circuit and also outputs the timeinformation which is brought into correspondence with theabove-mentioned audio information to a display means (step ST207), andthen returns to the normal playback process.

As mentioned above, when receiving the fast-forward playback releasesignal, the disc playback apparatus in accordance with this Embodiment 2sets up a position which is close to the release position and is locatedforwardly, by an arbitrary time, from the release position, as themovement destination of the optical pickup 2, whereas when receiving thefast-backward playback release signal, the disc playback apparatuscalculates a position which is close to the release position and islocated backwardly, by an arbitrary time, from the release position, asthe movement destination of the optical pickup 2. Therefore, thisEmbodiment 2 offers the same advantage as that provided by Embodiment 1.

In above-mentioned Embodiments 1 and 2, the disc playback apparatuscalculates the movement destination of the optical pickup on the basisof the time information. As an alternative, the disc playback apparatuscan calculate the movement destination of the optical pickup on thebasis of the position of the optical pickup.

INDUSTRIAL APPLICABILITY

As mentioned above, the disc playback apparatus in accordance with thepresent invention moves the optical pickup to a position which is closeto the position of the disc at where the information currently beingplayed back is stored when receiving a request for either a fast-forwardplayback or a fast-backward playback. Therefore, the disc playbackapparatus is suitable for use as a vehicle-mounted disc playbackapparatus exhibiting good responsibility when such a request asmentioned and release are repeated continuously and equipped with askipping preventing function, and so on.

1. A disc playback apparatus which temporarily stores information of adisc read by an optical pickup in a memory, and which reads theinformation stored in said memory to play back the information,characterized in that said disc playback apparatus comprises: a signaldecoder for decoding information read by said optical pickup; a timeinformation processor for processing time information from theinformation decoded by said signal decoder; a search controller forreceiving either a fast-forward playback request or a fast-backwardplayback request; a search target calculator for, when said searchcontroller receives either of said requests, performing a calculatingoperation by setting up a position which is close to a playback positionof said disc as a movement destination of said optical pickup on a basisof the time information processed by said time information processor;and a disc controller for controlling a servo for driving said opticalpickup, and characterized in that said search controller instructs saiddisc controller to move said optical pickup on a basis of a result ofthe calculating operation performed by said search target calculator. 2.The disc playback apparatus according to claim 1, characterized in thatwhen said search controller receives the fast-forward playback request,said search target calculator calculates a position which is close tothe playback position and is located forwardly, by an arbitrary time,from the playback position as the movement destination of said opticalpickup.
 3. The disc playback apparatus according to claim 1,characterized in that when said search controller receives thefast-backward playback request, said search target calculator calculatesa position which is close to the playback position and is locatedbackwardly, by an arbitrary time, from the playback position as themovement destination of said optical pickup.
 4. (canceled)